The insulated gate bipolar transistor (IGBT) is generally used in a manner of a reverse parallel freewheeling diode. However, on one hand, this manner results in waste of the package area; on the other hand, due to the existence of parasitic effects such as a parasitic inductor, the parallel additionally increases the power consumption. Therefore, the technology of integrating the IGBT and the diode in a same chip is increasingly emphasized.
The back side N+ type and the P+ type of the conventional reverse conducting insulated gate bipolar transistor (RC-IGBT) spread the whole back side of the IGBT. When turning on the diode, a large number of holes is injected via the positive pole (the emitter of the IGBT), a part of which come into the cathode through the N-drifting region of the terminal. When recovering reversing of the diode, the holes stored below the terminal cannot be empty and disappear quickly. The recovering characteristic of the diode has to be improved by the controlling technology for the carrier lifetime such as irradiation.